Regulation of induction of P450IA1 (P-450E) in teleosts was examined by investigating temporal relationships between P-450E protein, activity, and mRNA levels, and measuring protein and heme turnover in the teleost Fundulus heteroclitus. Monoclonal antibodies used for P-450E protein detection were specific in immunoblots for purified scup (Stenotomus chrysops) P-450E, a single band corresponding to P-450E in scup microsomal mixtures, and the xenobiotic-inducible orthologue in other fish including Fundulus. P-450E mRNA was measured by translation of total RNA, precipitation with anti-P-450E polyclonal antibodies and autoradiography, or by hybridization of RNA with a trout P450IA1 cDNA. P-450E and ethoxyresorufin O-deethylase activity rose coordinately after treatment with Beta-naphthoflavone, lagging behind mRNA increases by about 25 hours. mRNA levels declined rapidly, despite prolonged elevated protein and activity levels. In a dual label experiment, P-450E was precipitated from solubilized microsomes. The apoprotein was calculated to have a half-life of 32 to 43 hours, the heme moiety a longer half-life of 104 hours. These results support a hypothesis that transcriptional enhancement is involved in initial stages of P-450E induction, while other forms of control are important in maintenance of P-450E expression. The study addressed a specific chemico-biological interaction - the organism's biochemical response to a challenge by foreign compounds - which occurs in the marine environment. (Copyright (c) Pamela J. Kloepper-Sams, 1989.)